Synchronize Application Objects With DataSet

I sometimes come across patterns or common practices that I do not agree with. I have a clear opinon of what is considered "good design", which is mainly based on my understanding of abstraction and creating layers.IMO, the core of an application is it's object model. It's a hierarchic model where one object references other objects or lists of them. That's a memory-internal model. For example, a house object references a list of rooms referencing lists of furniture.An object is identified by it's reference. There are no IDs or PKs in that layer.Saving/Loading data is an additional feature. Sure, no application will do without, but it's based on top of the core of the application. I could write an application that works very well without loading/saving, and for version 2 I will think about whether to save data to a database or an XML file. Merely this fact proves that a database layer is not the lowest. I've never agreed with that three-tier model - even if you call me unteachable.

In addition to all application objects, there are Datasets - and that's my problem now. They can be considered as a copy of what is already present in the application's object model. Its from a different, table-oriented view. As both structures exist in parallel, there's the need to synchronize the DataSet with the (rest of the) application's objects.That's the task that I am always struggling with, and I ask how you handle it. I know this is a major design question but, fortunatelly, I could quite get around this problem so far.The only solution I can imagine is maintaining additional relation lists. For example, whenever the property of a room object changes, that change must be reflected in the associated DataRow in the DataSet. For this purpose, I need a look-up table that tells me the PK of the given room in the database. It requires a lot of additional efforst to do all the synchronization.Again, the house or room object itself does not have a PK and it won't get one because on that layer, it doesn't even know that a database exists.